Fire extinguisher



5 Sheets-Sheet 1 Filed Oct. 25, ;957

INVEN TOR.

Wi/l/am W Peferson Fig. 3

ATTORNEYS Dec. 29, 1959 w. w. PETERSON 2,918,976

.FIRE EXTINGUISHER Filed Oct. 25, 1957 3 Sheets-Sheet 2 INVENTOR.

W///iam W Peferson Y A TTORNEYS Dec. 29, 1959 w. w. PETERSON 2,918,976

FIRE EXTINGUISHER Filed Oct. 25, 1957 5 Sheets-Sheet 3 INVENTOR.

William W Pe/erson v I BY 1/ -l,,'/ M

A TTORNEYS United States Patent FIRE EXTINGUISHER William W. Peterson, Grand Rapids, .Mich., assignor to Anderson-Bolling Manufacturing Company, Spring Lake, Micln, a corporation of .Michigan Application October 25, 1957,'Serial.No. 692,450

15 Claims. (Cl. 169-31) This invention relates to a .fire extinguisher generally and more particularly to a valve control mechanism.

Numerous different means have been proposed for operating the exhaust valve mechanism of fire extinguishers; particularly those for home use which are infrequently used and then generally under conditions of high excitement and irrationality. The difiiculties which have been experienced in providing a suitable exhaust control valve and operating mechanism therefor have included providing an air tight sealing valve and a valve which is resealable after partial use, as well as a control mechanism which is readily operable and takes as little physical effort as possible in order that the average workman, housewife or rational teen-age child may manipulate the controls.

It is here proposed to provide an exhaust valve and related control mechanism for use with fire extinguishers which includes the aforementioned advantageous features, as well as other important features which will become more obvious with reference to a fire extinguisher structure adapted to include such features and which is hereinafter described and illustrated.

In the drawings:

Fig. 1 is a cross-sectional view of the exhaust valve control mechanism of a fire extinguisher container, only part of which is show, as seen in the plane of lines II of Fig. 3.

Fig. 2 is similar to Fig. 1 except for having the valve mechanism and interrelated control means shown in a different position.

Fig. 3 is a top view of a fire extinguisher including the novel features of the invention, having parts thereof shown in cross-section in the plane of line IIIIII of Fig. 1 and looking in the direction of the arrows thereon.

Fig.4 is an enlarged cross-sectional view of a part of the valve control mechanism as taken along the plane of line IV-IV of Fig. 3.

Fig. 5 is an exploded view of the different parts of the disclosed fire extinguisher exhaust valve and related control mechanism with certain parts broken away and shown in cross-section. Only one half of the control handle and associated parts are shown in Fig. 5, it being understood that the other part thereof is identical with that which is shown.

The fire extinguisher illustrated comprises a bottle or cylindrical container within which a fire extinguishing chemical and/or compressed gas is disposed. A neck member 12 is secured within the open end of the container and is adapted to receive a valve and exhaust passageway housing member 14 in threaded engagement therewith, as at 16, and further sealed thereto as by an O ring 18.

Intersecting passageways and 22 are formed through the housing member 14, axially and radially thereof, respectively. Passageway 22 is threaded to receive an extinguisher exhaust nozzle 24 therein (Figs. 1 and 2) while passageway 20 which extends through both ends of 2,918,976 Patented Dec. 29, 1959 the housing is formed to receive a reciprocal valve member 26 therein.

The lower end of passageway '20, below the exhaust nozzle passageway 22, is enlarged and has a conical valve seat 28 formed at the upper end thereof while the lower end is threaded to receive a fitting 30 to which the feed conduit 32 extending into the container 10, is secured. An 0 ring seal 34 is also provided between the fitting and the lower end of the housing member, as shown by Figs. 1 and 2.

The upper end of passageway 20, above the exhaust nozzle passageway 22, is sized to provide a sleeve hearing portion 36 for a complementary part 38 of the stem 40 of the valve member 26 aforementioned. The upper end of the passageway 20 opens into a chamber portion 42 within which certain valve operating mechanism is disposed, as will later be described.

The valve member 26 is reciprocally disposed within passageway 20, as has been mentioned, and is guided by the portion 38 of the valve stem 40 slidably journalled within part 36 of the passageway. An 0 ring seal 44 is provided about the valve stem, for sealing purposes, as is shown in Figs. 1 and .2. The lower end of valve stem 40 is threaded, as at 46. It slidably receives a flanged collar member 48 having a resilient valve seating member 50 bonded thereto. A cap screw 52 is threaded onto the extreme end of the shaft.

The valve seating member 50 is generally frustroconical in shape and includes several rows of annular ridges 53 about its outer surface for better sealing engagement with the valve seat 23. As will be appreciated by a comparison of the normal shape of the seating member 50, seen in Fig. 2, and that assumed upon engagement with the valve seat 28, shown in Fig. l, the seating member resiliently assumes the more conical form of the valve seat upon being engaged therewith and the annular ribs or ridges 52 are urged into tight sealing engagement therewith. Due to the fact that stem 49 slides in the collar 48, when an upward force is applied to the stem the valve member 50 is squashed, within its elastic limit, causing it to form a tight seal with the valve seat 28. The valve member itself acts like a spring when the force is released and by its inertia will open the valve.

The upper end of the-valve stem 40 is formed to include a pair of stepped shoulders 54 and 56, as best seen by Fig. 2, upon which are loosely mounted the disc or plate members 58 and 60. A lock nut 62 is threaded on the end of the shaft stem 40 to positively assure the seating of the plate 60 on the shoulder 56 and because of the stepped relation of the shoulders the plate members are disposed in substantially parallel spaced relation to each other.

The plate members 58 and 60 are both disposed within chamber 42 and move relatively therein as the valve member 26 travels between the closed and open positions thereof, shown by Figs. 1 and 2, respectively.

The upper or open end of chamber 42 is closed by a cover member 64 which, in this instance, is engaged with the housing 14 by having staked parts 66 provided on the rim thereof, which telescope over the end of the housing member and snap into engagement within an annular groove 68 formed about the end of the housing. A spring member 70 is in compressed engagement between the cover member 64 and the upper disc or plate 60 on the valve shaft to bias the valve shaft in a valve opening position to the limits permitted, as upon a seating of the lower plate 58, on the valve shaft, against the lower extremity of chamber 42.

The valve controlling mechanism includes a handle 72 having the ends thereof secured to bushings 74 and 76 journalled within receiving accesses 78 and 80 provided in opposite sides of the housing 14 at the upper end thereof. The handle 72 can takemany forms. In this instance, it is flat stock rolled to a semi-tubular cross section, as shown in Figs. 1 and 2, and having a gap 82 therein which provides afinger grip on the handle. The ends of the handle are formed to receive the bushings 74 and 76 therein by being flanged, as at 84, for such pur pose. Bolts 86 and 88 respectively secure bushings 74 and 76 to the handles. The bushings will be noted to have a spherical or ball surface thereon, as at 90 engaging the sidewalls of the housing forming the accesses 78 and 80, which forms a less frictional ball-joint type journalling of the bushings.

An eccentric in the form of a bar or rod 92 is rotatably received within slots 94 and 96 provided in the outer periphery of the bushings 74 and 76, respectively, which places such bar in an eccentric position with respect to the rotation of the bushings. The bar receiving slots 94 and 96 are disposed diametrically opposite the handle secur ing bolts 86 and 88, which are also eccentrically received by the bushings, as best shown by Fig. 4. The off center location of the bolts 86 and 88 assure against rotation of the bushing members relative to the handle portion secured thereto and the disposition of the rod ends across therefrom is for the best distribution of load forces to the bar 92 as received from the handle connection to the bushing members, as will later be described.

The bushings 74 and 76 are each rotatable about a common axis that extends diametrically across the housing member and through chamber 42, provided in the upper end thereof. The bar 92 extends between the bushings and across the chamber 42, between the plate members 58 and 60 which are secured to the upper end of the valve shaft 40, and has a bend or kink 98 therein adjacent the valve shaft to prevent interference therewith as will be described.

The bar 92 being disposed between the plates 58 and 60 on the valve shaft, and being eccentrically movable with the bushings 74 and 76, controlled by handle 72 is relatively movable between the plates in a radial direction and at the same time moves vertically within chamber 42 carrying with it the plate members and consequently reciprocating the valve stem 40 to open and close the valve member 26. Movement of the bar member 92 in a vertical direction, to open the valve 26, on either side of a plane formed by the reciprocal axis of the valve shaft 40 and the axis of rotation of the bar-carrying bushings 74 and 76, is assisted by the force of spring 70 which continuously tends to open the valve.

It is important to a specific aspect of this invention that the bar 92 be adapted to move from one side of the plane just mentioned to the other side thereof in order to take advantage of the spring efliort to open the valve, thereby requiring much less effort on the part of a person operating handle 72 to do so, and to provide the over-center valve locking feature which is next described. broadest aspect however, this feature is not necessary.

As previously mentioned the rod 92 is formed with abend 98 therein next adjacent the valve shaft 40. This enables the bar 92 to be disposed on one side of the valve shaft, as shown by Figs. 1 and 3, and still be able to pass to the other side thereof, as shown by Fig. 2; the sides of the valve shaftmentioned being those on opposite sides of the plane formed by the intersecting axis of the bushings and valve shaft members.

In order to coordinate the handle positions for an open or closed valve with the disposition of the valve actuating rod member 92, the bushing members 74 and 76 are secured to the ends of handle 72, with the handle in its lowered position, as shown in Fig. 1, (which will be noted is opposite the exhaust nozzle 24) so that the eccentrically disposed slots 94 and 96 in the bushings for receiving the ends of the bar 92 are near the top of the bushings, and on the side of the reference plane previously mentioned, whereby the spring 70 tends to rotate the bushings in a clockwise direction as seen in the view of Fig.1. In

In the 4 this position of the bar and handle the valve 26 is in a closed position.

As the handle 72 is raised from the position shown by Fig. 1 to the position shown by Fig. 2, the bar member 92 travels across the reference plane and on the other sidethereof the spring 70 tends to rotate the bushings 74 and 76 in a counter-clockwise direction, as best appreciated by reference to Fig. 2. This means that the spring force is assisting the handle in opening valve 26 and therefore much less effort is required by the person operating the handle to do so.

With bar member 92 disposed on the over-center side of the valve stem 40, as shown by Fig. 1, there is a tendency for the valve spring to again open the valve by the clockwise rotation of the bushings towards a bottom center disposition. This is prevented both by the fact that further rotation of the bushings would cause handle 72 to engage the side of container 10 to stop the action, and also by detents 100 and 102 formed in the plate member 58. These detents are engaged by the bar 92, in the course of its relative movement between the plates during clockwise rotation of the bushings members, and prevent further movement of the bar and consequently any further rotation of the bushing members. The detents are preferably disposed to stop the bar just short of engagement of the bend 98 therein with the valve shaft, to prevent any binding, and to stop the handle 72 just short of engagement with the container 10, which enables a better grip to be had on the handle.

Although the over-center action of the spring member 70 adequately holds the valve 26 in a closed position, a quick release safety latch 104 is provided which includes the ring member with the cotter-pin ends received through an access 106 in the housing wall and engaged between the plate members 58 and to prevent any vertical movement thereof. This pin can be the sole means for positioning the valve closed if the over-center action is eliminated.

From the description of the disclosed fire extinguisher just given its operation should be quite obvious. The equipment is kept in the condition shown by Fig. 1; the valve 26 closing passageway 20 between the container 10 and the exhaust nozzle 24, the spring acting on bar 92 to open the Valve but not sufficiently to unseat the valve, bar 92 held in an over-center position against 'detents 109 and 102 and preventing further rotation of the bushings 74 and 76, handle 72 held off from container 10, and the locking pin 104 received between the plate members 58 and 60 to positively prevent reciprocation of the valve member. Upon the release of the safety latching pin 104, and a raising of the handle 72 to rotate the bushings 74 and 76 in a counter-clockwise direction, the bar 92 travels past the top-dead-center position and the spring 76 assists the opening of the valve to the extent permitted by the bottoming of plate 58 within chamber 42, as shown by Fig. 2, and the content of the container is free to escape through passageway 20 and nozzle 24.

The claims appended hereto define the invention which is to be considered comprehensive of all forms of structure coming within this scope.

I claim:

1. A fire extinguisher actuating mechanism compris ing: a housing member having a passageway formed therethrough with a valve seat; a source of fire extinguishing material and an exhaust means communicating with said passageway; reciprocal valve actuating means disposed within said passageway between said source and said exhaust means; a resilient valve element attached to said valve actuating means and adapted to seat on said "alve seat; said valve element being compressible within a predetermined elastic limit when forced against said valve seat; actuator means for determining the position of said valve element, said actuator means being movable on a path which crosses the reciprocal axisof the valve actuatingmeans' andsoneach side of said axis takes a course having a component extending in a valveopening direction; said actuator means engagingsaid valve actuating means so as to be simultaneously movable therewith in the valve ope'ning'and closing direction; said path on one side of said axis-extending a sufiicient distance in the valve opening direction to permit 'said valve actuator means to unseat said valve elementfro'm said valve seat and said actuator means followslsaid path; said path on the other side of saidaxis extending a distance in the valve opening direction less than the compressible elastic limit of said resilient valve element; limit stop means for confining the movement of said actuator means to 'said'path;='and-spring means operatively associated with said valve actuating means for biasing said valve actuating means in the direction of said parallel component whereby when said .valve actuator is on said one side of said axis it aids in biasing the valve element open but when on the other side of said axis it aids in holding the valve closed.

2. The fire extinguisher actuating mechanism of claim 1, wherein; said actuator means includes a cam element eccentrically mounted on a rotatable support means having its axis of rotation intersecting said reciprocal axis, said cam element engagingusaid valve actuating means and movable on said path upon rotation of saidrotatable support means.

3. The fire extinguisher actuating mechanism of claim 2 including: spaced shoulder portions'provided upon said valve actuating means and extending onopposite sides of the reciprocal axis thereof, said spring means bearing against said shoulder portions on both sides of said reciprocal axis; said actuator means being an elongated cam member extending between said space shoulder portions; and means for moving said elongated cam member along said path. I

4. The fire extinguisher actuating mechanism of claim 1: said actuatormeans including the end of a, control member rotatively journalled within said housing member about an axis intersecting the reciprocal axis of said valve actuating means and having a cam part eccentrically disposed of the rotative axis thereof, and shoulder portions comprising spaced plate means provided on the end of said reciprocal valve actuating means and engaged by said eccentrically disposedcam part; thercam part being adapted to move along saidapath in the course of rotation of said control member.

5. A valve actuating mechanism comprising: reciprocal valve actuating means reciprocally mounted on a given axis; a valve seat; a valve element movable with said valve actuating means in avalve closing direction and a valve opening direction; resilient cushioning means associated with said valve element -and valve actuating means and arranged to be compressed within predetermined elastic limits in the course of the closing of said valve element on said valve seat; actuator means for determining the position of said valve element, said actuator means being movable on a path which crosses the reciprocal axis of the valve actuating means and on each side of said axis takes a course having a component extending in a valve opening direction; said path on one side of said axis extending a sufiicient distance inthe valve opening direction to permitsaid valve actuator to unseat said valve element from said valve seat as said valve actuator follows said path; said path on. the other side of said axis extending a distance in the valve opening direction less than the elastic limit of said resilient cushioning means; and limit stop means for confining the movement of said actuator means to said path.

6. A fire extinguisher control mechanism, comprising: a housing member having passages formed therethrough with a valve seat and a source of fire extinguishing substance and an exhaust means connected to saidipassages; a reciprocal valve actuating member disposed within said housing within a passage thereof between said source and-said exhaust means; a resilient valveelement attached to said valve actuating means and adapted to seatonsaid valve seat, said valve element being compressible within a predetermined elastic limit when forced against said valve seat; a valve actuator means having partsthereof rotatably engaged with said housing on opposite sides thereof and on an axis intersecting the reciprocal axis of said valve actuating member intermediate the ends thereof; a valve engaging cam member extending between said parts eccentrically of the axis of rotation of said parts; said cam member being movable along apath'forming a portion of a circle which path crosses the reciprocal axis of the valve actuating member and on each side of said axis takes a course having a component extending in a valve opening direction; said cam member engaging said valve actuating member so that said valve actuating member is simultaneously .movable therewith in the valve opening and closing direction; said'path on one side of said axis extending a suflicient distance in the valve opening direction to permit said cam member to unseat said valve element from said valve seat as it follows said path; said path on the other side of said axis extending-a distance in the valve opening direction less than the compressible elastic limit of said resilient valve element; limit stop means for confining themovement of said cam member to said path; spring means operatively associated with said valve actuating member for biasing said valve actuating member in the valve opening direction'whereby when said valve engaging cam member is on said one side of said axis it aids in biasing the valve open but when on the other side of said axis it aids in holding the valve closed.

7. The fire extinguisher control mechanism of claim 6 including spaced shoulder portions provided upon the controlled end of said valve actuating member and engaged by said eccentrically mounted valve engaging cam member, and said limit stop means including stops on said shoulder portions disposed on said other side of said reciprocal axis and engaged by said valve engaging cam member to limit its movement on said path.

8. The fire extinguisher control mechanism of claim 6; thecontrol end of said valve actuating member having spaced shoulders provided thereon; plate members disposed upon said shoulders in spaced relation to each other; said spring means being engaged with one of said plates; and said valve engaging cam means being disposed between and engaged with both of said plate members.

9. A valve having a housing with a passageway formed therein, a valve seat in said passageway, and a reciprocal valve element disposed within said passageway for seating on said valve seat, the improvement comprising: a stem attached to said valve element and extending through said passageway; a pair of spaced shoulders on the end of said stem opposite said valve element; spring means engaging one of said shoulders comprising spaced plate means for biasing said valve in an open position; means rotatable on said housing on opposite sides of said shoulders about an axis intersecting the reciprocal axis of said valve; a cam bar attached to said last mentioned means and extending between the spaced shoulders; said cam bar being mounted eccentrically about the axis intersecting said reciprocal axis whereby rotation of said means moves the bar along acircular path which crosses the reciprocal axis of the stem and on each side of said axis takes a course having a component-extending in a valve opening direction; resilient cushioning means associated with said stern and valve element, and compressible within predeterminedelastic limits when said stem forces said valve element against said seat; said path on one side of said axis extending a sufficient distance in the valve opening direction to permit said cam bar to unseat said valve element from saidvalve seat as it follows said path; said path on'the other side of said axis extending a distance element; means rotatable on said housing about an axis intersecting the reciprocal axis of said valve; a cam bar attached to said last mentioned means and extending between the spaced plates; said cam bar being mounted eccentrically about said axis whereby rotation of said means moves the bar along a circular path which crosses the reciprocal axis of the stem and on each side of said axis takes a course having a component extending in a valve opening direction; resilient cushioning means associated with said valve element and stem, and compressible within predetermined elastic limits when said stem forces said valve element against said seat; said path of said cam bar on one side of said axis extending a sufficient distance in the valve opening direction to permit said cam bar to unseat valve element from said valve seat as said cam bar follows said path; said path on the other side of said axis extending a distance in the valve opening direction less than the elastic limit of said cushioning means; limit stop means for confining the movement of said actuator means to said path; and said cam bar including an oiiset portion adjacent said valve stem to avoid interference therewith in moving across the reciprocal axis of said valve.

11. A valve having a housing with a passageway formed therein, a valve seat in said passageway and a reciprocal valve means in said passageway having a valve element for seating on said valve seat, the improvement comprising: spring means disposed within said housing and engaged with said valve means for biasing said valve element off said seat. in an opening directionfand an actuator means rotatively mounted Within said housing about an axis substantially intersecting the reciprocal axis of said valve means, said actuator means being movable on a path which crosses the reciprocal axis of the valve means and on each side of said axes takes a course having a component extending in a valve opening direction; said actuator means engaging said valve means so that said valve means is simultaneously movable therewith in the valve openingand closing direction; resilient cushioning means associated with said valve means and compressible within predetermined elastic limits when said stem forces said valve element against said seat; said path on one side of said axis extending a sufiicient dis-.

tance in the valve opening direction to permit said actuator means to unseat said valve element from said valve seat as said actuator means follows said path; said path on the other side of said axis extending a distance in the valve opening direction less than the elastic limit of said cushioning means; and limit stop means for confining the movement of said actuator means to said path.

12. A valve useful as a fire extinguisher mechanism having a housing with a passageway formed therein, a valve seat in said passageway, and a reciprocal resilient valve element disposed within said passageway for seating on said valve seat, said valve element being compressible with predetermined elastic limits when forced to seat on said valve seat the improvement comprising:

spring means disposed within said housing and engaged with said valve element for biasing said valve element in an opening direction; a stem attached to said'valve element and extending through said passageway; a pair of spaced shoulders comprising spaced plate means on the end of said stem opposite said valve element; means rotatable on said housing on opposite sides of said shoulders about an axis intersecting the reciprocal axis ofsaid 8 valve; a cam bar attached to said last mentioned means and extending between the spaced shoulders; said cam bar being mounted eccentrically on' said axis'whereby rotation offsaid means moves the 'bar on a path which crosses the reciprocal axis of the said stem and on each side'of said axis takes a course having a component extending in a valve ope ning direction; said path on one side of said axis extending a suflicient distance in the valve opening direction to permit said cam bar to unseat said valve element from said valve .seat as said cam bar follows said path; said path on the other side of said axis extending a distance in the valve opening direction less than the elastic limitof said resilient valve element; and limit stop means for confining the movement of said actuator means to said path. i

13. A valve arrangement for the control of a pressurized fluid disposed withina closed fire extinguisher container, and comprising: a valve housing having passageways formed therethrough, one of said passageways being in open communication with said container, a valve seat formed within said one passage and accessible from the direction of said container, a resilient valve member engaged on said seat and held thereon by the pressure of the fluid within said container, said valve member including a resilient element compressible within predetermined elastic limits when forced against said seat and connected to a valve stem reciprocal within said one passage way, parallel spaced plates mounted on said valve stem normal to the axis thereof, an actuator means received between said plates for reciprocating said valve stem between open and closed positions, said actuator means including an offset portion adjacent said valve stem to avoid interference therewith in the course of movement normal to said stem to permit said actuator means to cross the axis of said valve stem, said resilient valve engaging said valve seat prior to the travel of said actuator means across said axis and being compressed in the course of such travel, a biasing spring engaged with one of said plates for urging said valve in a valve opening direction, said actuator means being movable on a path which crosses the reciprocal axis of said valve stem and on each side of said axis takes a course having a component extending in a valve opening direction;'said path on one side of said axis extending a suflicient distance in the valve opening direction to permit said actuator means to unseat said valve member from said valve seat as said actuator means follows said path; said path on the other side of said axis extending a distance in the valve opening direction less than the elastic limit of said valve'element, and a limit stop provided between said spaced plates and engaged by said eccentric operator for preventing said spring .from uns'eating said valve when said operator is disposed on said other side of the reciprocal axis of said valve stem.

14. A valve actuating mechanism comprising: reciprocal valve actuating means reciprocally mounted on a given axis; a valve seat; a valve element movable with said valve actuatingmeans in a valve closing direction and a valve opening direction; resilient cushioning means associated with said valve element and valve actuating means and'arranged to be compressed within predetermined elastic limits in the course of the closing of said valve element on said valve seat; actuator means for determining the position of said valve element, said actuator means being movable on a path which crosses the reciprocal axis of the valve actuating means and on each side of said axis takes a course having a component extending in a valve opening direction; said path on one side of said axis extending a sufiicient distance in the valve opening direction to permit said valve actuator to unseat said valve'element from said valve seat as said valveactuator follows said path; said path on the other side of said axis extending a distance in the valve opening direction less than the elastic limit of said resilient cushioning means; limit stop means for confining the movement of said actuator means to said path; and spring means operatively associated with said valve actuating means for biasing said valve element in a valve opening direction whereby when said valve actuator is on said one side of said axis it aids in biasing the valve element open but when on the other side of said axis it aids in holding the valve closed.

15. A fire extinguisher actuating mechanism comprising: a housing member having passageway formed therethrough with a valve seat; a source of fire extinguishing materal and an exhaust means communicating with said passageway; reciprocal valve actuating means disposed within said passageway between said source and said exhaust means; a resilient valve element attached to said valve actuating means and adapted to seat on said valve seat; said valve element'being compressible within a predetermined elastic limit when forced against said valve seat; actuator means for determining the position of said valve element, said actuator means being movable on a path which crosses the reciprocal axis of the valve actuating means and on each side of said axis takes a course having a component extending in a valve opening direction; said actuator means engaging said valve actuating means so as to be simultaneously movable therewith in the valve opening and closing direction; said path on one side of said axis extending a sufiicient distance in the valve opening direction to permit said valve actuator means to unseat said valve element from said valve seat as said actuator means follows said path; said path on the other side of said axis extending a distance in the valve opening direction less than the compressible elastic limit of said resilient valve element; limit stop means for confining the movement of said actuator means to said path.

References Cited in the file of this patent UNITED STATES PATENTS 1,164,775 Anderson Dec. 21, 1915 1,718,730 Brown June 25, 1929 2,238,693 Geertz Apr. 15, 1941 2,294,594 Bloomfield Sept. 1, 1942 2,642,083 Strong June 16, 1953 2,753,945 Beebee et a1. July 10, 1956 

